JSC Electric CUT-OUT EXHAUST
#21
RE: JSC Electric CUT-OUT EXHAUST
ORIGINAL: lv360ram
Isn't zero exhaust restriction the best? Could someone explain the need for backpressure?
Isn't zero exhaust restriction the best? Could someone explain the need for backpressure?
#22
RE: JSC Electric CUT-OUT EXHAUST
scavanging doesn't help pull exhaust gases of the next cylinder, scavanging causes the incoming air to be forced in more, that's why the intake and exhaust are open at the same time. the exhaust leaving causes a vacuum causing the incoming air to be forced in more. another reason why race cars run open headers or very short pipes is becuase they are running very high compression. A blower or a turbo raises your copression ratio. Nascars are running around17 to 1 compression. our stock motors i believe are around 8.9 to 1....pretty big difference uh? also scavanging helps out more in lower rpms then in higher rpms. so if your running in the rpm range of 4000 to 5000 rpms all day long, then no backpressure might be good. guess how much rpms nascars are at??? close to 15000 rpms all day long
#23
RE: JSC Electric CUT-OUT EXHAUST
ORIGINAL: spaz_22
scavanging doesn't help pull exhaust gases of the next cylinder, scavanging causes the incoming air to be forced in more, that's why the intake and exhaust are open at the same time. the exhaust leaving causes a vacuum causing the incoming air to be forced in more. another reason why race cars run open headers or very short pipes is becuase they are running very high compression. A blower or a turbo raises your copression ratio. Nascars are running around17 to 1 compression. our stock motors i believe are around 8.9 to 1....pretty big difference uh? also scavanging helps out more in lower rpms then in higher rpms. so if your running in the rpm range of 4000 to 5000 rpms all day long, then no backpressure might be good. guess how much rpms nascars are at??? close to 15000 rpms all day long
scavanging doesn't help pull exhaust gases of the next cylinder, scavanging causes the incoming air to be forced in more, that's why the intake and exhaust are open at the same time. the exhaust leaving causes a vacuum causing the incoming air to be forced in more. another reason why race cars run open headers or very short pipes is becuase they are running very high compression. A blower or a turbo raises your copression ratio. Nascars are running around17 to 1 compression. our stock motors i believe are around 8.9 to 1....pretty big difference uh? also scavanging helps out more in lower rpms then in higher rpms. so if your running in the rpm range of 4000 to 5000 rpms all day long, then no backpressure might be good. guess how much rpms nascars are at??? close to 15000 rpms all day long
#24
RE: JSC Electric CUT-OUT EXHAUST
ORIGINAL: spaz_22
scavanging doesn't help pull exhaust gases of the next cylinder, scavanging causes the incoming air to be forced in more, that's why the intake and exhaust are open at the same time. the exhaust leaving causes a vacuum causing the incoming air to be forced in more. another reason why race cars run open headers or very short pipes is becuase they are running very high compression. A blower or a turbo raises your copression ratio. Nascars are running around17 to 1 compression. our stock motors i believe are around 8.9 to 1....pretty big difference uh? also scavanging helps out more in lower rpms then in higher rpms. so if your running in the rpm range of 4000 to 5000 rpms all day long, then no backpressure might be good. guess how much rpms nascars are at??? close to 15000 rpms all day long
scavanging doesn't help pull exhaust gases of the next cylinder, scavanging causes the incoming air to be forced in more, that's why the intake and exhaust are open at the same time. the exhaust leaving causes a vacuum causing the incoming air to be forced in more. another reason why race cars run open headers or very short pipes is becuase they are running very high compression. A blower or a turbo raises your copression ratio. Nascars are running around17 to 1 compression. our stock motors i believe are around 8.9 to 1....pretty big difference uh? also scavanging helps out more in lower rpms then in higher rpms. so if your running in the rpm range of 4000 to 5000 rpms all day long, then no backpressure might be good. guess how much rpms nascars are at??? close to 15000 rpms all day long
they dwell in the vecinity of 6500-just shy of 10 most of the racing occurs (dependant upon track) at 8-9500
now indy cars, thats another issue all together, they run up about that high(15000), with comp ratios up to 23:1
#25
RE: JSC Electric CUT-OUT EXHAUST
no they run around 13000 to 15000rpms during races.. we had a couple of nascars come to school while i was in the chassis and high performance motor class at wyotech. we didn't get to hear it run at 1500 but he reved it to 8000 and it sounded pretty damn nice and got there pretty quick.
#26
RE: JSC Electric CUT-OUT EXHAUST
ORIGINAL: spaz_22
no they run around 13000 to 15000rpms during races.. we had a couple of nascars come to school while i was in the chassis and high performance motor class at wyotech. we didn't get to hear it run at 1500 but he reved it to 8000 and it sounded pretty damn nice and got there pretty quick.
no they run around 13000 to 15000rpms during races.. we had a couple of nascars come to school while i was in the chassis and high performance motor class at wyotech. we didn't get to hear it run at 1500 but he reved it to 8000 and it sounded pretty damn nice and got there pretty quick.
"...To coax their pushrod designs to rev higher without running out of breath, engineers have designed lighter, stiffer, lower-friction valvetrains. Pushrod V-8 engines racing in Nascar routinely rev to 9,000 rpm. Thanks to natural trickle-down, the lightweight valves, low-friction lifters and high-tension valve springs made of exotic steels have filtered into production pushrod engines, giving them the speed and stamina to compete with Ferrari’s V-8. While the F-430’s screaming 8,500 r.p.m. maximum speed is still out of reach, the 7,000-r.p.m. redline of the Corvette outdoes the 6,600-r.p.m. maximum of the Porsche 911 Turbo. The new Viper engine revs to 6,200 r.p.m., 200 more than before...."
from http://www.nytimes.com/2007/01/14/au...yt&emc=rss
(just over half way down the page easest to find by searching "nascar" on the page)
#27